VENTURA, Calif. (Reuters) - A raging California wildfire powered by fierce winds grew into the third-largest in state history on Saturday as forced evacuations turned neighborhoods into ghost towns and ash fell in some areas like heavy snow.

High winds and dry conditions were expected to remain through the weekend to power the so-called Thomas Fire in Southern California. It has destroyed more than 1,000 structures and threatened 18,000 more since erupting on Dec. 4, including homes in the wealthy enclave of Montecito just outside the coastal city of Santa Barbara.

Nearly 8,500 personnel using nearly 1,000 engines and 32 helicopters were battling the blaze, which was 40 percent contained on Saturday evening. It has become the seventh-most destructive in state history, officials said.

A new evacuation order was issued for parts of Santa Barbara County on Saturday as high winds whipped the fire through bone-dry terrain.

In Montecito, smoke billowing from nearby canyons and pushed by the high winds choked the air, hindering aircraft from dropping flame retardant, the Governor’s Office of Emergency Services said.

The wildfire forced many schools to close for days, shut roads and drove hundreds of thousands from their homes. It was also responsible for poor air quality throughout Southern California.

An evacuation order for the city of Ventura, which was hit hard in the first days of the fire, was lifted on Saturday morning.

“Our backyard, it’s like a rain of ash. I don’t even want to step back there,” said Janet Harrington, 56, an artist and writer who grew up and lives in Ventura.

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This year has been unprecedented for California in terms of structures lost and the size of the wildfires, officials said. Five of 20 most destructive fires in recorded history ravaged the state in 2017, according to Cal Fire.

The vast landscape charred by the blaze, centered fewer than 100 miles (160 km) northwest of downtown Los Angeles, reached 267,500 acres (108,253 hectares) late on Saturday. The largest wildfire in state history was the 2003 Cedar blaze in San Diego County that consumed 273,246 acres and caused 15 deaths.

The hot Santa Ana winds have propelled the fire’s expansion, at times sending embers far ahead of its main flank. They were forecast to gust at up to 50 mph (80 kph) on Sunday with critical fire conditions remaining through Monday, National Weather Service forecasters said.

Cal Fire engineer Cory Iverson, 32, died on Thursday while battling the flames near the Ventura County community of Fillmore. Fire officials said Iverson, the blaze’s first fatality, left behind a pregnant wife and 2-year-old daughter.

He died of smoke inhalation and burns, the Ventura County Medical Examiner’s office said.

Reporting by Alex Dobuzinskis and Caroline Anderson; Additional reporting by Dan Whitcomb in Los Angeles, and Barbara Goldberg in New York; Writing by Jon Herskovitz; Editing by Mary Milliken and Paul Tait